<form class="form-signin" role="form">
    <h2 class="form-signin-heading">注册</h2>
    <input type="text" class="form-control" placeholder="Email..." required="" autofocus="">
    <input type="password" class="form-control" placeholder="密码" required="">
    <input type="button" class="btn btn-lg btn-primary btn-block" value="注册">
</form>